Hepatitis-C-virus-induced microRNAs dampen interferon-mediated antiviral signaling

Area of Science:

• Virology
• Immunology
• Molecular Biology

Background:

• Hepatitis C virus (HCV) causes chronic infections in millions globally, leading to severe liver disease.
• HCV establishes persistence by suppressing host antiviral defenses, including interferon responses.
• Previously identified host microRNAs (miRNAs), miR-208b and miR-499a-5p, suppress type III interferons (IFNL2/3) during HCV infection.

Purpose of the Study:

• To investigate the role of miR-208b and miR-499a-5p in modulating type I interferon signaling during HCV infection.
• To determine if inhibiting these miRNAs can restore antiviral responses in HCV-infected hepatocytes.

Main Methods:

• HCV-infected human hepatocytes were treated with miRNA inhibitors targeting miR-208b and miR-499a-5p.
• Expression levels of IFNAR1, type I and III interferons, and interferon-stimulated genes were quantified.
• HCV viral load was measured following miRNA inhibition and exogenous type I interferon treatment.

Main Results:

• miR-208b and miR-499a-5p were found to directly down-regulate the type I interferon receptor chain (IFNAR1) in HCV-infected hepatocytes.
• Inhibition of these miRNAs increased IFNAR1 expression and restored sensitivity to exogenous type I interferon.
• MiRNA inhibition led to increased interferon-stimulated gene expression and a significant decrease in HCV viral load.

Conclusions:

• HCV utilizes miR-208b and miR-499a-5p to suppress both type I and type III interferon pathways.
• These miRNAs target IFNAR1, dampening the type I interferon response and promoting viral persistence.
• Targeting these specific miRNAs represents a potential therapeutic strategy to enhance antiviral immunity against HCV.